This is a known scam. Most times the person sending the private key will ask you to assist them in moving their coins claiming that they don't have any idea on how to do it themselves and afterwards provide you with the private key to the wallet. The reason why they do this is to try to trap those with greedy mindsets, those that are looking for how to steal money they didn't work hard to get.
When you finally import the wallet you'll be asked for add some gas fee and as soon as you add Tron to the wallet it will be moved automatically to another wallet. I believe that Tron can allow multisig so even if youre possession of one of the account that's need to sign the transaction you still won't be able to send anything away from that wallet.

Most times when I receive messages like this I immediately report them to telegram so that their account can be suspended or restricted from sending messages to non mutual contact that way it will help slow down their activities.